Efficient Battery-Powered Meter

ABSTRACT

Techniques for the design and operation of an efficient battery-powered meter are described herein. A metrology unit of the meter may be at least partially located in the gas flow of a pipe, and measures gas flow rate data according to a static flow sensor. The metrology unit calculates raw gas-volume data using at least the flow rate data as input. The metrology unit measures gas temperature to produce gas temperature data, and adjusts the raw gas-volume data, based at least in part on the gas temperature data, to produce corrected gas-volume data. The metrology unit accumulates the corrected gas-volume data over multiple minutes, hours or even days, and then sends the accumulated corrected gas-volume data to an index unit of the meter. By accumulating the data over time, fewer data transmissions are required. The index unit may send the accumulated the accumulated corrected gas-volume data to a utility server.

RELATED APPLICATIONS

This patent application is a continuation of and claims priority to U.S.patent application Ser. No. 15/714,900, filed on Sep. 25, 2017, titled“Efficient Battery-Powered Meter,” which claims priority to U.S. patentapplication Ser. No. 62/399,799, filed on Sep. 26, 2016, titled“Modular, Power Efficient Battery Powered Meter,” both of which arecommonly assigned herewith, and hereby incorporated by reference.

BACKGROUND

Utilities such as gas, water and electric services that are provided tocustomers are typically metered at the customer's location. Powerconsumption by the meter is an issue in gas and water meters, becausethese meters are typically battery powered. Also, cost is a concern,because of the aggregate cost of the meters used by millions ofcustomers across the country.

The power used by gas meters is typically consumed by sensor and analogfunctions, data processing, and data communications. Management of thesepower expenditures is important, due to design requirements for batterylife.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Thesame numbers are used throughout the drawings to reference like featuresand components. Moreover, the figures are intended to illustrate generalconcepts, and not to indicate required and/or necessary elements.

FIG. 1 is a block diagram showing an example network in which a utilitymeter includes a metrology unit and an index unit.

FIG. 2A is a block diagram showing a first example of components withinthe metrology unit and the index unit.

FIG. 2B is a block diagram showing a second example of components withthe metrology unit and the index unit.

FIG. 3A is a block diagram showing an example operational sequence ofprocessing within a utility meter, and showing a first division offunctionality between the metrology unit and the index unit.

FIG. 3B is a block diagram showing an example operational sequence ofprocessing within a utility meter, and showing a second division offunctionality between the metrology unit and the index unit.

FIG. 4 is a flow diagram showing operation of an example metrology unit.

FIG. 5 is a flow diagram showing operation of an example metrology unit.

FIG. 6 is a flow diagram showing operation of an example metrology unit.

FIG. 7 is a flow diagram showing operation of an example metrology unit.

FIG. 8 is a flow diagram showing operation of an example metrology unit.

FIG. 9 is a flow diagram showing operation of an example metrology unit.

FIG. 10 is a flow diagram showing operation of an example index unit.

FIG. 11 is a flow diagram showing operation of an example index unit.

FIG. 12 is a flow diagram showing operation of an example index unit.

FIG. 13 is a flow diagram showing operation of an example index unit.

FIG. 14 is a flow diagram showing example operation of a meter includinga metrology unit and an index unit.

FIG. 15 is a flow diagram showing several example techniques by which amessage with data may be sent from the metrology unit to the index unit.

FIG. 16 is a flow diagram showing example techniques by which ametrology unit is operated.

FIG. 17 is a flow diagram showing example techniques by which ametrology unit is operated.

DETAILED DESCRIPTION Overview

The disclosure describes techniques for more efficiently processingmetrology data in a manner that conserves battery power and network ordata-bus bandwidth in a natural gas, water or other utility meter, andparticularly in the functioning of a metrology unit and an index unit.In an example of the techniques, the metrology unit processes flow ratemeasurements to calculate a raw gas volume. The metrology unit thenperforms calculations using temperature data to correct the raw gasvolume data and to create corrected gas volume data. Advantageously, thetemperature data can be discarded (e.g., overwritten in memory) ratherthan transmitted to the index unit. This results in a substantialsavings of battery power and data bus bandwidth. The metrology unit thenaccumulates corrected gas volume (or water volume) data for latertransmission, which may be in response to a demand from the index unit.Also advantageously, the transmission of corrected gas volume data isnot time-critical, in contrast to the transmission of flow rate data inknown gas meters. Accordingly, considerable savings in power, batterylife and intra-meter data transmission results.

Example Systems and Techniques

FIG. 1 shows an example system 100 in which a utility meter 102 includesa metrology unit 104 and an index unit 106. The utility meter 102 may beconfigured to measure gas, water or other product used by a utilitycustomer. The metrology unit 104 may measure fluid flow through a pipe108. The fluid may be gas or water. The metrology unit 104 may examineaspects of the fluid flow and generate data related to fluid speed,temperature, volume, vibration, or other characteristics.

The metrology unit 104 may communicate resource information to the indexunit 106. In one example of the communication, the index unit 106requests or pulls resource information from the metrology unit 104. Therequest may be in the form of a message, interrupt signal or othertechnique. In an alternative example of the communication, the metrologyunit sends the resource information to the index unit according to amutually recognized and/or understood schedule. In a further example ofthe communication, the metrology unit pushes the information to theindex unit. The index unit 106 communicates consumption related databack to a server(s) 110 of a utility provider. In the example system100, one or more intermediaries may be used to transmit data (e.g.,consumption data) from the utility meter 102 to the utility provider110. In one example, the index unit 106 communicates consumption relateddata via wireless electromagnetic signal 112 to a reader device 114.Data may be moved from the reader device 114 by cable or radio frequency(RF) connection to a utility server 110, through one or more networks118, or other means. In another example, the utility meter 102 (e.g., byoperation of the index unit 106) communicates consumption related datato a person via a display. The person then inputs the consumptionrelated data into reader 114. In further example, the utility meter 102and/or index unit 106 communicates consumption related data via wirelesselectromagnetic signal 116 to one or more devices in network 118. Inthis example, the device(s) in the network 118 may be one or more ofanother utility meter, a collection node, a cellular base station, orother communication device. The network 118 may be a compound network,such as including public, proprietary and/or utility company networks,and/or the internet, and/or other network combinations.

Using the reader device 114 and/or network 118, data (e.g., customerutility consumption data) arrives at the utility server 110 from indexunit 106 of the utility meter 102. The utility provider uses theconsumption related data at utility server 110 to take one or moreutility-related actions such as, generating a bill, identifying usagepatterns, allocating utility resources, responding to system leaks,initiating utility service turn-ons or shut-offs, or other actions.

The utility meter 102 may be include an enclosure 120. The metrologyunit 104 may also have an enclosure 122, through which there is a gasflow 122 and connections to the pipe 108. The gas flow measurementprocess is performed by the metrology unit 104, and totalized data isreported to the index unit 106, which may be contained within anenclosure 124. The gas flow 122 is therefore contained within theenclosure 122 of the metrology unit 104, and the index unit 106 isseparated from that flow.

FIG. 2A shows an example of components of a utility meter 102 having ametrology unit 104 and an index unit 106, and thereby shows a possibleimplementation of the devices shown in FIG. 1. In one example, metrologyunit 104 and index unit 106 are implemented as physically separatedevices coupled by a link 200. One advantage of this separatedimplementation is that the maintenance of the combined system (e.g.meter 102) is simplified. For example, in a gas meter, with separatedimplementation, if the index unit 106 fails, it can be replaced withoutdisturbing the metrology unit 104 interface with the gas pipe.Similarly, if communication conditions between the index unit 106 andnetwork 118 or reader 114 are difficult, the location of the index unitcan be moved without disturbing the metrology unit 104 and/or itsinterface to the gas pipe. Separate implementation of the metrology unit104 and index unit 106 also facilitates flexibility and simplicity indesigning metering systems that use different measurement techniques. Inthe example of a gas meter, a single index unit 106 can be alternativelypaired with metrology units using different technologies, such asmechanical fluid measurement techniques, ultrasonic fluid measurementtechniques, thermal mass flow measurement, or other measurementtechniques. This allows a single index unit 106 to be used in systemsutilizing different metrology technologies, which results in manufactureand supply efficiencies.

Metrology unit 104 includes one or more sensors 202. In one example, aplurality of sensors 202 may be present in the metrology unit 104. Inthe example, a metrology sensor 202 may include one or more of anultrasonic sensor, a temperature sensor, a tilt sensor, a thermal massflow sensor, and/or other sensor(s). Other sensors may be related totemperature, tilt (e.g., tilting of the unit 104, indicating possibletampering) and other factors. The sensors 202 are coupled to processor204. In one example, the processor 204 is an ASIC, FPGA, general purposemicroprocessor, microcontroller, system or PC on a chip/card, or otherprocessing mechanism. While shown as a single block, processor 204 maybe implemented as one or more separate devices. In one example, thesensors 202 pass sensor readings to the processor 204. Processor 204 iscoupled to memory 206. While shown as separate blocks, processor 204 andmemory 206 may be implemented as a single device or as multiple devices.Processor 204 sends sensor readings obtained from sensors 202 to thememory 206 for storage. In one example, processor 204 performs one ormore operations on the sensor readings such as accumulation, measurementrefinement and/or improvement, temperature data acquisition, utilizationand/or storage, or other calculations. Processor 204 may also utilizeappropriate drivers and hardware devices to communicate with the indexunit 106.

Processor 204 is coupled to interface 208. In one example, interface 208is a multi-pin connector, which may be support by one or more integratedcircuits, as required by a particular design. In an example, two or morepins of interface 208 provide connections for power, return and/orground from link 200, to thereby provide power and ground for one ormore components in the metrology unit 104. For example, a first set ofpins in interface 208 provides a first ground and power (e.g., 3 volts)for processor 204. A second set of pins may provide power (e.g., 12volts) and ground for valve motor 210. In another example, one or morepins of interface 208 are used for communications between metrology unit104 and index unit 106. The communications may be serial, parallel,proprietary and/or according to a standard. In one example,communications between the metrology unit 104 and index unit 106 areperformed over a serial link through interface 208, cable 200 andinterface 212. The components of the metrology unit 104 may receivepower, ground and communication lines that are routed directly orindirectly (e.g., through other components) from interface 208. Themetrology unit 104 may utilize data and/or power busses or printedcircuit wiring, which may be connected to the interface 208, to providepower and data connectivity to some or all devices.

In one example, metrology unit 104 includes valve motor 210. Valve motor210 operates to open or close a valve, and to thereby provide full orpartial control over the volume or rate of flow of a material, such asgas or water, through a pipe to which the metrology unit 104 isattached. The valve motor 210 may be coupled to processor 204, a powerand/or data bus, or directly to interface 208. Alternatively oradditionally, the valve motor 210 may be attached to the motor driver224 over the interface and link 200. Accordingly, the motor driver 224and/or the processor 204 may provide control signals and/or power to thevalve motor 210 to facilitate opening or closing a valve in the pipe(e.g., pipe 108 of FIG. 1).

Metrology unit 104 is coupled to index unit 106, such as via wired,optical and/or RF connection 200. In one example, connection 200 is amulti-wire connector, cable and/or conductor that provides power andcommunication connections and throughput. In the example shown,connection 200 is coupled by wiring or cable, between interface 208 ofthe metrology unit 104 and the interface 212 of index unit 106. In animplementation having a wired connection, the metrology unit 104 mayreceive power from the index unit 106.

Index unit 106 may include a radio 214. In one example, radio 214includes a power amplifier, transmitter, receiver, filters, switches,and other circuitry to support wireless RF communication. The radio 214is coupled to one or more antennas to transmit and/or receive wirelesssignals. In one example, the signals are sent to or from the reader 114or device(s) in network 118 (both shown in FIG. 1). While shown aswithin index unit 106, the antenna may be housed within, partiallywithin, or outside of the index unit. The radio 214 may be coupled toprocessor 216. In one example, processor 216 is similar to processor 204and is implemented as one or more ASICs, FPGAs, microprocessors or otherprocessing mechanisms. Processor 216 is coupled to memory 218, such asby a data bus connecting some or all of the devices of the index unit106. While shown as separate blocks, processor 216 and memory 218 may beimplemented as a single device or multiple devices.

Processor 216 may be coupled to interface 212, either by direct wiring,printed circuit board, or one or more data and/or address busses. In oneexample, interface 212 is similar to interface 208 of metrology unit 104and enables the supply of power to the metrology unit 104 from the indexunit 106 and the exchange of communication between the two units. In oneexample, processor 216 receives metrology information from metrologyunit 104 via the connector 200 and the interface 212. The processor 216stores the metrology information in the memory 218. In one example, theprocessor 216 performs one or more operations on the metrologyinformation such as accumulation or mathematical calculations and storesthe result in the memory 218. In one example, the processor 216 sendsthe metrology information to reader device 114 or devices in network 118(both shown in FIG. 1) via the radio 214 and associated antenna.

Index unit 106 includes a power supply 220 coupled to a battery 222. Thebattery 222 may include one or more cells and/or batteries. The powersupply 220 draws power from the battery 222 and suppliesvoltage-regulated power to one or more elements of index unit 106 ormetrology unit 104. In one example, the power supply 220 provides powerat a first voltage and/or current level to elements such as processor216 and processor 204 and power at a different voltage level to motordriver 224 and a power amplifier within radio 214. Accordingly, thepower supply 220 provides consistent and/or desired voltage levels atdifferent output current levels and/or different battery voltages (e.g.,as the battery discharges). The power supply 220 may be coupled toprocessor 216, memory 218, radio 214, motor driver 224 and othercomponents of the index unit 106 through direct connections or use of apower bus of the index unit. The power supply 220 may also supply powerto elements of metrology unit 104 through interface 212, connector 200and interface 208.

In one example, index unit 106 includes a motor driver 224. The motordriver 224 may be coupled to data and power buses, or directly to theprocessor 216. The motor driver 224 may also, or in the alternative, becoupled to valve motor 210 through interface 212, connector 200, andinterface 208. In one example, motor driver 224 supplies one or moresignals and/or power levels to valve motor 210 to cause the valve motorto open or close a valve, and turn on or shut off the flow of fluidthrough a pipe to which the metrology unit 104 is attached.

In one example, index unit 106 includes one or more sensors 226 coupledto processor 216. In one example, sensors 226 may include a tilt sensor,a vibration sensor, a leak detector, and/or other sensors. In oneexample, information from a sensor 226 is used by processor 216 inperforming calculations on data received from metrology unit 104. Inanother example, information from sensor 226 is communicated byprocessor 216 to the utility provider 110 (of FIG. 1) for use indecisions to turn on or shut off utility service to a customer.

A user interface 228 may include a screen to display information. In anexample, a worker may press a button and view data displayed responsiveto activation of the button. The viewed data may be keyed into thereader device 114 of FIG. 1, for transmission to the utility server 110.

The arrangement of elements seen in FIG. 2A is one example of componentselection and arrangement. In another example, the components used inthe metrology unit 104 and/or the index unit 106 may be replaced withdifferent component(s). Additionally, components, their equivalent,and/or their replacement, may be transferred between the metrology unit104 and the index unit 106. For example, the motor driver 224, thesensor 226, the power supply 220, and the battery 222 may be moved,removed, duplicated and/or rearranged between the metrology unit 104 andindex unit 106.

FIG. 2B shows an example of components of a utility meter 250 having ametrology unit 104 and an index unit 106, and thereby shows a possibleimplementation of the devices shown in FIG. 1. In the example shown, theutility meter 250 is similar to the meter 102 shown in FIGS. 1 and 2.However, the meter 250 is powered by internal batteries 258.Accordingly, the metrology unit 252 is able to totalize gas consumptiondata without power provided by the index unit 254. Moreover, themetrology unit 252 may be configured to calculate a gas volume that isaccurate to within a threshold value or threshold error, without theassistance or intervention by the index unit 254. The threshold value orallowed error may be based on legal and/or business requirements, suchas a particular fraction of a percent of inaccuracy.

Advantageously, the metrology unit 252 is a stand-alone unit.Accordingly, the index unit 254 may be replaced with a different unit ofthe same of different design without resulting in a need for re-design,re-calibration and/or re-certification (e.g., by governmental agency) ofthe metrology unit 252. This allows the index unit to be replaced formuch less cost than is the case wherein the metrology unit and the indexunit share components, software, power and/or roles in the calculationof gas volume data and/or totalized gas consumption data. Suchreplacement does not result in need to re-design, re-calibration and/orrecertify the metrology unit.

Metrology unit 252 includes one or more batteries 258, which may powervarious components, including one or more sensors 202, the processor204, memory 206, motor driver 224, valve motor 210, communicationsdevice 264 and/or other components. In the example shown, the batteries258 provide power to components through a power supply 260, whichprovides regulated voltages at desired current levels. Accordingly, asthe battery discharges, regulated power is provided to the components ofthe metrology unit 252.

An interface 260, 262 between the metrology unit 252 and the index unit254 may be wired or wireless. In the utility meter 250 of FIG. 2B, awireless interface may be used, in part because both units are poweredby their respective batteries, and wiring to provide power between unitsis not required. The interface 260, 262 may include communicationsdevices 264, 266, which may be based on optical, radio frequency,magnetic or other technologies.

FIGS. 3A and 3B show additional example configurations of utility meters300 and 350, respectively. Each meter is configured with a metrologyunit and an index unit. However, the location and/or design of severalfunctional blocks distinguish the two examples.

FIG. 3A is a block diagram showing an example sequence of processingwithin a utility meter 300, and showing a first division offunctionality between a metrology unit 302 and an index unit 304. In theexample, an interface 306 the metrology unit 302 communicates with aninterface 308 of the index unit 304. While the interface 306, 308 isshown as a wired serial interface, parallel interfaces, radio frequency,magnetic, optical and other technologies could be substituted. A pair ofultrasonic transducers 310 is representative of gas-flow sensingdevices. The ultrasonic transducers 310 provide one or more outputsignals to a processor 312. In the example shown, ultrasonic transducersare defined at least in part in hardware. In a possible configuration,the ultrasonic transducers send one or more acoustic waves in oppositedirections, and measure a differential time of transmission of the twowaves to produce a gas velocity signal. The ultrasonic transducers 310or a different device may measure the gas temperature, which is providedto the processor 312. A T (temperature) functional block 314 may bedefined within the processor, and may be configured to receivetemperature data as input. The T block 314 may be configured tocondition the received temperature signal for transmission to the serialinterface, such as for further use, such as for meter calibration. Thetemperature information processed at block T 314 may sent to theprocessor 326 for use by a C factor block 316 (i.e., temperaturecompensation factor block). While the T block 314 is shown in themetrology unit 302 and is operated by the processor 312, the rawtemperature data could be passed through to the index unit 304 of themeter 300, and the T block could be located in the index unit 304 andcould be executed by the processor 326. The C factor block 316 uses thetemperature information to produce data usable to refine the calculatedgas volume measurements according to gas temperature and the basetemperature. A dt block 318 processes signal timing measurementinformation, which may be in the nanosecond range (or other range, asindicated by design requirements). The dt block may process a differencein time measurement of an ultrasonic signal sent upstream and anultrasonic signal sent downstream. Such signals may be considered to betime upstream (T-up) and time downstream (T-down). Such signals may beincrementally (i.e., very slightly) different, as a result of the gasmovement (flow) as the signals move through the gas stream. Thedifference may be used to assist in the calculation of the gas flowvelocity. The differential time signals may be sent to the V (m/s) block320, where the velocity of the gas stream (e.g., in meters per second)is calculated. The velocity may be calculated in part by considerationof ultrasonic signal path length, angle of signal transmission and otherfactors. At a Q(l/h) block 322, a cross-section of the gas flow isdetermined and/or applied. The length/height notation may also representmore complex calculations of the cross-section. Accordingly, the blocks320 and 322 calculate information from which it is possible to derivegas flow according to velocity and a cross-section through which the gasmoves. The gain block 324 is used as a control on signal strength andamplitude, and helps to compensate for gas temperature, gas pressure,gas composition and other factors. The gain block 324 may be configuredto receive and transmit information, so that the gain may be determinedbased on input received from the ultrasonic transducer. Also, the gainblock 324 may be configured to receive information so that a desiredlevel of gain (e.g., signal amplitude) may be set, and a data frameconfigured for transmission to the indexing unit 304 of the meter 300.The gain level may also be used to determine transducer functionality.For example, a high gain level and/or saturation in combination with alow signal level and/or erroneous data may indicate that the transducer310 is near its end-of-life. In another example, if the gain is above athreshold value, a failure of the ultrasonic transducer may be assumed.Data representing a volume of the gas flowing over time may beaccumulated over time in an accumulator. In the example shown, the Vm(m3) 328 block is located in the processor 326 accumulates volume of gas(e.g., in meters squared) as it is measured over time. The volumecalculated at Vm (m3) block 328 may be considered to be raw volume data,which is adjusted for temperature at Vb block 330. Output of the Cfactor block 316 may be used as input by Vb block 330 to calculate atemperature-adjusted gas volume.

FIG. 3B is a block diagram showing an example sequence of processingwithin a utility meter 350, and showing a second division offunctionality between the metrology unit 352 and the index unit 354. Inthe example, a processor 356 is configured to receive gain, gas flow andgas temperature data from the ultrasonic transducer 310. In theprocessor 356, the gain block 324, dt block 318, V (m/s) block 320,Q(l,h) block 322, T block 314 and C factor block 316 are similar to thearrangement seen in FIG. 3A. However, the Vm (m3) block 328, the Vbblock 330 and the meter calibration data block 332 are configured foroperation by the processor 356 of the metrology unit 352.

Example Message Transmission

FIGS. 4-17 are flow diagrams showing an example processes 400-1700 whichare representative of techniques for use in utility meters and otherdevices having internal communications. The processes may, but need notnecessarily, be implemented in whole or in part by the system 100 and/orthe meters of FIGS. 1 through 3. In some examples of the techniquesdiscusses herein, the methods of operation may be performed by one ormore application specific integrated circuits (ASIC) or may be performedby a general-purpose processor utilizing software defined in computerreadable media. In the examples and techniques discussed herein, thememory 206, 218 may comprise computer-readable media and may take theform of volatile memory, such as random access memory (RAM) and/ornon-volatile memory, such as read only memory (ROM) or flash RAM.Computer-readable media devices include volatile and non-volatile,removable and non-removable media implemented in any method ortechnology for storage of information such as computer-readableinstructions, data structures, program modules, or other data forexecution by one or more processors of a computing device. Examples ofcomputer-readable media include, but are not limited to, phase changememory (PRAM), static random-access memory (SRAM), dynamic random-accessmemory (DRAM), other types of random access memory (RAM), read-onlymemory (ROM), electrically erasable programmable read-only memory(EEPROM), flash memory or other memory technology, compact diskread-only memory (CD-ROM), digital versatile disks (DVD) or otheroptical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other non-transitorymedium that can be used to store information for access by a computingdevice.

As defined herein, computer-readable media does not include transitorymedia, such as modulated data signals and carrier waves, and/or signals.

FIGS. 4 through 9 are flow diagrams showing operation of an examplemetrology unit, such as metrology unit 104 of FIGS. 1 and 2. However,similar actions may alternatively be performed by a similar oralternative metrology unit.

FIG. 4 shows example operation 400 of a metrology unit, wherein datafrom sensor readings are sent to an index unit. At block 402, metrologyunit 104 performs a sensor reading. In one example, the sensor readingis a propagation time measurement, which may be performed by a pair ofultrasonic sensors. At block 404, the metrology unit 104 sends thesensor reading to the index unit 106. In one example, the metrology 104unit performs the sensor reading multiple times to ensure an accuratemeasure of the amount of a resource consumed. For example, with flowrate measurements, the measured flow rate can be converted to a volumemeasurement. If the flow rate measurements are taken close together, thederived volume from each flow rate measurement is an accurateapproximation of the actual volume of resource (e.g., fluid, gas, water)consumed since the last measurement. However, if the flow ratemeasurements are taken farther apart it is possible that the flow ratewill have changed significantly between measurements, and the volumecalculation from a flow measurement will not accurately approximate thevolume of resource consumed since the last flow measurement. In oneexample, to obtain sufficient accuracy, the metrology unit 104 performsan ultrasonic sensor reading of flow rate approximately every one or twoseconds. The reading is then sent by the metrology unit 104 to the indexunit 106. In one example, the reading is pulled by the index unit 106 asneeded or to fit a schedule, etc. In the example, the index unit 106 maysend a demand to the metrology unit 104, and receive data in response tothe demand.

FIG. 5 shows example operation 500 of a metrology unit, wherein datafrom sensor measurements are used in calculations, and the calculateddata is sent (e.g., in response to a demand, in a pull process) to anindex unit. At block 502, a metrology unit 104 performs a sensorreading. Block 502 may be performed in a similar manner to acorresponding block in the previous figure. At block 504, the metrologyunit 104 calculates a metric based on the sensor reading. In oneexample, the sensor reading is an ultrasonic sensor reading of flowrate. In this example, the metrology unit 104 converts the flow rateinto a volume metric. In another example, the metrology unit 104performs both a volume calculation and a temperature compensationcalculation on the sensor reading to generate a temperature-compensatedvolume metric. At block 506, the metrology unit 104 sends (e.g., inresponse to a demand from the index unit, in a “pull” process) themetric to the index unit 106.

In some circumstances, it is beneficial to reduce the number ofcommunications between the metrology unit 104 and the index unit 106.The amount of power used to communicate sensor readings or metrics fromthe metrology unit 104 to the index unit 106 represents a significantportion of the battery power energy used by the entire system. Thus, thereduction in the power for communications between these units results inadditional battery life, reduction in the size or number of batteries,or additional power available for other purposes.

FIG. 6 shows example operation 600 of a metrology unit, wherein dataaccumulation is performed, thereby allowing less frequent datatransmissions and correspondingly increased power savings. While theblocks are shown in a sequence, techniques described in two or moreblocks could be performed simultaneously. At block 602, a metrology unit104 performs a sensor reading. In one example, an ultrasonic sensorprovides a propagation time measurement, from which flow rate may becalculated. In an example, the calculations are performed at themetrology unit. At block 604, the metrology unit 104 accumulates thesensor reading. In one example the processor 204 takes the currentreading and adds it to an accumulated value in memory 206. At decisionblock 606, the metrology unit 104 determines if there has been asufficient, desired and/or threshold amount of accumulation ofaccumulated sensor readings and/or other data. In an example, theaccumulation is considered to be sufficient if the index unit hasrequested data from the metrology unit. The request may be part of a“pull” process, by which data is pulled from the metrology unit by theindex unit, or the request may be part of a “push” process, by whichdata is sent by the metrology unit without a corresponding data request.In one example, the metrology unit 104 determines completeness of theaccumulation by using a counter to track a number of accumulations toperform, or a period of time during which to accumulate. In anotherexample, the metrology unit 104 performs accumulations in an on-goingmanner. At intervals, the metrology unit 104 may receive a notification,request, demand and/or interrupt from the index unit 106. In the eventof such a demand from the index unit 106, the metrology unit proceeds toblock 608. At block 608, the metrology unit 104 sends the accumulatedsensor reading to the index unit 106. If the metrology unit detects nodemand from the index unit, the sensor and accumulation functionscontinue at block 602. Advantageously, by accumulating the sensorreadings at the metrology unit 104 the number of communications betweenmetrology unit 104 and the index unit 106 can be significantly decreasedwithout sacrificing the accuracy of the metering function. In oneexample, rather than communicating a sensor reading from the metrologyunit 104 every one or two seconds responsive to, or in synchronizationwith, the taking of the sensor readings, the metrology unit 104 can sendaccumulated sensor readings, e.g., responsive to a demand from the indexunit 106, every minute, every hour, every 12 hours, or even longer.Advantageously, the transmissions of accumulated data are nottime-critical. Accordingly, other time-critical events may be performed,and the reporting of accumulated data delayed or otherwise adjusted. Thebattery savings of the accumulation, and associated reduction intransmissions, are significant.

FIG. 7 shows example operation 700 of a metrology unit, wherein dataaccumulation and calculations are performed, thereby allowing lessfrequent data transmissions and correspondingly increased power savings.At block 702, the metrology unit 104 performs a sensor reading. At block704, the metrology unit 104 accumulates the sensor reading. At decisionblock 706, the metrology unit 104 determines if a request, demand orinterrupt has been received from the index unit, requesting data. Atblock 708, if a request was received, the metrology unit 104 calculatesa metric based on the accumulated sensor readings. At block 710, themetrology unit 104 sends the metric, calculated data, and/or theaccumulated data to the index unit 106, in response to the request atblock 706. If no request or demand was received at block 706, sensorreadings and accumulation continue, at blocks 702 and 704

FIG. 8 shows example operation 800 of a metrology unit, which in someconfigurations may be a slave with respect to the index unit. Therelationship may utilize techniques wherein the index unit “pulls” datafrom the metrology unit, such as by sending the metrology unit a demandfor data. Responsive to the demand from the index unit, the metrologyunit sends metrology data to the index unit. At block 802, metrologyunit 104 sends metrology unit data to the index unit 106. In oneexample, memory 206 includes one or more non-volatile memory devices. Inthis example, the non-volatile memory stores one or more of calibrationdata from the sensor 202, identification information for the metrologyunit 104, or other information. Advantageously, calibration oridentification information stored on the metrology unit 104 can increasethe modularity of the entire system. For example, if calibrationinformation is stored on the metrology unit 104 rather than on the indexunit 106, the metrology unit 104 can be calibrated separately from theindex unit 106. Further, the index unit 106 can be replaced easilywithout disturbing the metrology unit 104. In one example, data from themetrology unit is sent as a distinct message. In another example, datafrom the metrology unit may be sent as part of another message such asthe messages sent in steps blocks 404, 506, 608, or 710 of FIGS. 4, 5, 6and 7, respectively.

FIG. 9 shows example operation 900 of a metrology unit, wherein themetrology unit receives a configuration message, and subsequently sendsdata according to configuration instructions received in the message. Atblock 902, the metrology unit 104 receives a configuration message fromthe index unit 106. In one example, the configuration message isreceived in combination with an acknowledgement of a previoustransmission to the index unit 106. In one example, the configurationmessage contains a mode select indicator instructing the metrology unit104 to operate in a particular mode. In one example, the possible modescorrespond to one or more of the processes described with respect toflowcharts 400-800 of FIGS. 4 through 8. In another example, the modeindicator instructs the metrology unit to select between an accumulationmode, such as the processes 600 and 700 of FIGS. 6 and 7, and a discretemode, such as the processes of flow charts 800 and 900 of FIGS. 8 and 9,respectively. In another example, the configuration message indicateswhat metrology unit data, if any, should be included in a subsequentmessage from the metrology unit 104 to the index unit 106. At block 904,the metrology unit 104 performs one of the processes 400 through 800described with respect to FIGS. 4 through 8 responsive to theconfiguration message. In one example, the metrology unit 104 repeatsthe selected process until a new or different configuration message isreceived.

FIGS. 10 through 13 are flow diagrams showing example operation of anindex unit (e.g., index unit 106 of FIGS. 1 and 2). FIG. 10 showsexample operation 1000 of an index unit 106, wherein the index unitreceives a message from the metrology unit and sends or forwards theinformation over a network. At block 1002, the index unit 106 receives amessage from metrology unit 104. In one example, the message containsone or more of sensor readings, accumulated sensor readings, calculatedmetrics from a single sensor reading, calculated metrics fromaccumulated sensor readings, metrology data, or other information. Atblock 1004, the index unit 106 sends some or all of the information fromthe received message over the network 118 or to the reader 114. In oneexample, the transmission of the information may be delayed based on aschedule of the index unit 106 for reporting information over thenetwork 118 or to the reader 114.

FIG. 11 shows example operation 1100 of an index unit, wherein a messageis received, at the index unit and from the metrology unit, a metric iscalculated at the index unit, and the calculated metric and/or otherdata is sent over the network. At block 1102, the index unit 106receives a message from metrology unit 104. At block 1104, the indexunit 106 calculates a metric based on the message. In one example, theindex unit 106 determines a temperature compensated metric by performinga temperature compensation a volume metric received from the message. Atblock 1106, the index unit 106 sends information to the network 118 orthe reader 114. In one example, the information sent includes the metriccalculated on the index unit 106.

FIG. 12 shows example operation 1200 of an index unit 106, wherein amessage is received, the message or data from the message isaccumulated, and the accumulated information is sent over a network. Atblock 1202, the index unit 106 receives a message from metrology unit104. At block 1204, the index unit 106 accumulates the message content.In one example, the processor 216 of the index unit 106 takes thecurrent content from the received message and adds it to an accumulatedvalue in memory 218. In one example, the accumulated message content isvolume metrics calculated by the metrology unit 104. In this example,the index unit 106 may receive the volume metrics once per minute butmay send the volume information to the utility in hourly consumptionunits. Thus, the index unit 106 accumulates smaller increments until anhourly accumulation is complete. At decision step 1206, the index unit106 determines if sufficient accumulation has been recorded. In oneexample, as described above, the accumulation is based on a usage timeunit, such as 15 minutes, an hour, or day. If the accumulation is notcomplete, the index unit 106 returns to block 1202. If the accumulationis complete, the index unit proceeds to block 1208. At block 1208, theindex unit 106 sends accumulated information to the network 118 or thereader 114. In one example, the index unit 106 may also perform acalculation on the accumulated information before sending theaccumulated information to the network. In one example this calculationis similar to the calculation performed in block 1104 of FIG. 11.

FIG. 13 shows example operation 1300 of an index unit, wherein aconfiguration message is sent to a metrology unit and at least one of aplurality of different actions may be subsequently performed. At block1302, the index unit 106 sends a configuration message to the metrologyunit 104. In one example, the configuration message is sent incombination with an acknowledgement of a previous transmission from themetrology unit 104. In another example, the configuration messagecontains a mode select indicator instructing the metrology unit 104 tooperate in a particular mode. In another example, the possible modescorrespond to one or more of the processes described with respect tomethods 400 through 900 of FIGS. 4 through 9. In another example, themode indicator instructs the metrology unit 104 to select between anaccumulation mode, such as the processes 600, 700 of FIGS. 6 and 7, anda discrete mode, such as the processes of 800 and 900 of FIGS. 8 and 9.In another example, the configuration message indicates what metrologyunit data, if any, should be included in a subsequent message from themetrology unit 104 to the index unit 106. At block 1304, the index unit106 performs one of the processes 1000 through 1200 described withrespect to FIGS. 10 through 12 upon receiving a message from metrologyunit 104 responsive to the sending of the configuration message. Inanother example, the index unit 106 repeats the selected process until anew or different configuration message is sent.

Example Methods

FIG. 14 shows example operation 1400 of a meter configured to include ametrology unit and an index unit. The metrology unit and the index unitmay be configured as a single unit, or as two discrete unitscommunicating over a wired or RF link. At block 1402, in the metrologyunit, flow rate data may be generated according to readings from astatic flow sensor. The flow rate data may be obtained from a flow ratesensor, such as a pair of ultrasonic transducers, which may be locatedin the metrology unit of the meter. The flow rate may be sampledfrequently, such as every two seconds.

At block 1404, at the metrology unit, the flow rate data are used incalculations to produce raw gas-volume data. By performing thecalculations in the metrology unit, the cost in battery power of sendingthe flow rate data to the index unit is not incurred. Such transmissionsare particularly power-intensive, due to both their frequency andtime-criticality.

At block 1406, at the metrology unit, gas temperature is measured toproduce gas temperature data. The temperature sensor may be astand-alone sensor, or may be integrated with the flow rate sensor. Themeasurements may be made at a frequency or timing that is the same ordifferent from the flow rate measurements.

At block 1408, at the metrology unit, the raw gas-volume data isadjusted using the gas temperature data, to produce corrected gas-volumedata. By performing the calculation at the metrology unit, there is nobattery cost of sending the temperature data to the index unit.

At block 1410, at the metrology unit, the corrected gas-volume data isaccumulated, typically for over a minute, or as long as twelve hours ormore. Sending flow rate data every two seconds, as is done by knownsystems, has a substantial battery-power cost. In one example, theaccumulation process maintains a running total of the correctedgas-volume data. By accumulating data over a period of one minute, onehour, twelve hours or one day, the cost in battery power of datatransmission is greatly reduced over conventional meters and systems.

At block 1412, a message is sent, such as from the metrology unit and toan index unit of the meter. In an example, the message may be pulled bya demand from the index unit, and sent from the metrology unitresponsive to the demand. The message may include data associated withthe accumulated, temperature-corrected gas-volume data, representing gasflow over the time of accumulation. At block 1414, in a first example ofthe transmission of the message of block 1412, other communications,such as between the index unit and a network node, may be made. Thecommunication of block 1414 may be, through coincidence or schedule,approximately the same time as transmission of the message of block1412. Because the message of block 1412 is not time-critical, thecommunication at block 1414 may delay transmission and receipt of themessage sent at block 1412. Due to the flexibility of when the messageof block 1412 is sent, slower and more power-efficient hardware devicesmay be used. At block 1416, in a second example of the transmission ofblock 1412, the index unit and/or the metrology unit may be involved inthe performance of tasks at approximately the time of the transmissionof block 1412. However, because the message of block 1412 is nottime-critical, the communication at block 1412 may be delayed. Thetime-flexibility of the sending of the message at block 1412 is based atleast in part on the ability of the metrology unit to accumulate dataover longer and/or shorter periods of time. This flexibility can resultin less expensive hardware, more flexible hardware design, and lowerbattery power consumption.

At block 1418, the accumulated corrected gas-volume data is transmittedfrom the index unit and to a utility server. At block 1420, in a firstexample, the accumulated gas-volume data is transmitted to the utilityserver by way of a reader device, such as reader device 114 of FIG. 1.At block 1422, in a second example, the accumulated gas-volume data istransmitted to the utility server through one or more networks, such asnetwork 118 of FIG. 1.

At block 1424, gas (or more generally, fluid) temperature data and/ordata elements may be discarded and/or overwritten in memory after thedata is used, such as in calculations that adjust the raw gas-volumedata to obtain corrected gas-volume data at block 1408. This actionprovides significant savings of battery power and savings of datatransmission bandwidth over known systems that transmit temperature datafrom the metrology unit and to the index unit. By performingcalculations that use the temperature data (e.g., conversion of rawgas-volume to corrected gas-volume) in the metrology unit, the indexunit does not need the temperature data. In some example embodiments,temperature data may be pulled from the metrology unit by the indexunit, and used by the index unit for purposes such as display, tamperevidence, etc.

At block 1426, the metrology unit may be calibrated usingmeter-calibration data. At block 1428, in one example, the generating offlow rate data at block 1402, the calculating of raw gas-volume data atblock 1404, and/or the measuring of gas temperature data at block 1406,or other functionality, is calibrated at the metrology unit.

FIG. 15 shows several example techniques 1500 by which a message withdata, e.g., accumulated corrected gas-volume data, may be pulled fromthe metrology unit by a demand sent by the index unit. Accordingly, theblocks of FIG. 15 may be performed in the alternative, or in someinstances and/or systems, in combination. The techniques 1500 may bevariations of, or examples of, block 1412 of FIG. 14.

At block 1502, in an inspection mode, test mode, an alarm condition, analarm status, and/or an alarm mode, an interrupt may be sent, from themetrology unit and to the index unit. The interrupt may be configured towake the index unit from a low-power consumption period, state or mode.The message of block 1412 is then sent, from the metrology unit to theindex unit, responsive to the interrupt. Accordingly, the message issent responsive to an interrupt, sent from the metrology unit and to theindex unit, wherein the interrupt is configured to wake the index unitfrom a low-power consumption period, state or mode. At block 1504, ademand for a message, is sent by the index unit and received at themetrology unit. The message is sent, from the metrology unit and to theindex unit, responsive to the demand. Accordingly, the message is sentresponsive to a demand for the message, wherein the demand was sent bythe index unit. At block 1506, a scheduled time for the message isrecognized. The recognition of the schedule may be by both the metrologyunit and the index unit. The message is then sent, based at least inpart on the scheduled time. Accordingly, the message is sent responsiveto a scheduled time for the message. At block 1508, an alarm conditionmay be present. In an example, the alarm condition could be related tofree-flowing gas, which may result from a broken pipe. Responsive to analarm condition, an interrupt is sent from the metrology unit (whichrecognized the alarm condition) to the index unit. The interrupt may beconfigured to wake the index unit from a low-power consumption period,mode or state, if necessary. The message is then sent, followingtransmission of the interrupt. Accordingly, the message is sentresponsive to an alarm condition.

FIG. 16 shows example techniques 1600 by which a metrology unit isoperated. At block 1602, flow rate data is generated, at a metrologyunit of a meter, according to a static flow sensor.

At block 1604, the flow rate data is processed, at the metrology unit ofthe meter, to produce gas-volume data processing. At block 1606, in afirst example of the processing of block 1604, the flow rate data isprocessed to produce raw volume data. At block 1608, the raw volume datais processed, based at least in part on measured temperature, to producethe corrected gas-volume data. At block 1610, in a second example of theprocessing of block 1604, gas temperature is measured, at the metrologyunit, to produce gas temperature data. At block 1612, raw gas-volumedata is adjusted, at the metrology unit, using the gas temperature data,to produce corrected the gas-volume data.

At block 1614, the gas-volume data is accumulated, at the metrology unitof the meter. In some systems, the data may be accumulated for multipleminutes, hours, or even days before it is pulled from the metrology unitby a demand from the index unit. At block 1616, data is pulled from themetrology unit by a demand or request from an index unit of the meter.The data may include the accumulated gas-volume data.

FIG. 17 shows example techniques 1700 by which a metrology unit isoperated. In the example shown, the metrology unit may be configuredaccording to the techniques shown, described and associated with FIG.2B. The utility meter 250 having a metrology unit 104 and an index unit106 is configured so that the metrology unit is battery powered, anddoes not depend on the index unit for power or for assistance inmeasuring gas velocity or for calculating gas consumption to within alegally allowed threshold error value. Accordingly, the index unit 106may be replaced without having to recertify the newly paired metrologyunit and index unit.

At block 1702, the gas flow is directed through an enclosure of ametrology unit, within which a metrology sensor, a processor and amemory device are all powered by a battery within the enclosure.Referring to the example of FIGS. 1 and 2B, the metrology unit 252includes a metrology sensor 202, a processor 204, a memory device 206, abattery 258 and a power supply 260 that are all within the enclosure 122(of FIG. 1). At block 1704, power is provided to the metrology sensor,the processor, and the memory device from the battery and/or powersupply. Block 1706 shows an example illustrating how power may beprovided to components in the metrology unit. In the example, powerreceived from the battery may be regulated to control voltage atdifferent current flows and battery charge levels. FIG. 2B shows thatthe regulation may be performed within the enclosure of the metrologyunit 252 by the power supply 260. At block 1708, a velocity of the gasflow may be measured, such as by operation of a metrology sensor. In theexample of FIG. 2B, the metrology sensor 202 measures gas flow velocity.However, alternative technologies and sensors may be used. At block1710, a volume of the gas flow may be calculated by operation of aprocessor, such as by using values measured by the sensor(s) as input.The calculated volume be expressed as totalized data that is accurate towithin a threshold value. The threshold value may be required by legal,agency or governmental regulations. Block 1712 shows an exampleillustrating how the threshold value is selected to result in anaccurate calculation of totalized gas flow that does not have to berevised or made more accurate by operation of the index unit. In theexample of block 1712, the threshold value may selected to preclude, orobviate the need for, gas volume calculations by the index unit. Becauseof the accurate measurement by the metrology unit, replacement of theindex unit 254 does not require recertification of the accuracy of thetotalized gas volume calculations of the metrology unit 252. At block1714, the totalized data is transmitted from the metrology unit to anindex unit. Blocks 1716 and 1718 show an example method by which thetransmission may be made. At block 1716, a communication device,configured for inductive, optical or radio frequency communication, isused to communicate with the index unit. At block 1718, thecommunications device allows communication between the metrology unitand the index unit, such as over an interface configured for wirelesstwo-way communication. In the example, the interface allows themetrology unit to send the totalized data to the index unit. In anexample use, at block 1720, a motor, powered by the battery and a motordriver, may be operated to close a valve and shut off the gas flow. Thebattery, motor driver, motor and valve may be located within theenclosure of the metrology unit.

CONCLUSION

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described. Rather,the specific features and acts are disclosed as exemplary forms ofimplementing the claims.

What is claimed is:
 1. A metrology device, comprising: a metrologysensor to measure gas flow; a processor configured to receive data fromthe metrology sensor and to calculate gas volume; a memory device tostore the data from the metrology sensor; a battery to power themetrology sensor, the processor and the memory device; and an enclosureto enclose the metrology sensor, the processor, the memory device andthe battery, wherein an interior portion of the enclosure is configuredfor gas flow.
 2. The metrology device as recited in claim 1, wherein:the processor is additionally configured to calculate totalized data tohave accuracy that is within a threshold value prior to transmission,the metrology device additionally comprising: an interface configured totransmit the totalized data to an index unit.
 3. The metrology device asrecited in claim 1, additionally comprising: a motor, powered by thebattery and configured to shut off the gas flow; and a motor driver,powered by the battery, wherein the motor driver provides logic andcontrol circuitry to operate the motor.
 4. The metrology device asrecited in claim 1, additionally comprising: an interface configured forwireless two-way communication with an index unit, wherein the wirelesstwo-way communication provides gas consumption data to the index unit,and wherein the gas consumption data comprises raw data that has beenprocessed to create data indicating usage over time periods.
 5. Themetrology device as recited in claim 1, additionally comprising: acommunication device configured for at least one of inductive, opticalor radio frequency communication with an index unit.
 6. The metrologydevice as recited in claim 1, wherein metrology unit is configured forgas measurement calculation independent of an index unit.
 7. Themetrology device as recited in claim 1, wherein: the metrology sensor isconfigured to measure velocity of gas flow; and the processor calculatesgas volume using data based on the gas flow without action by an indexunit.
 8. A metrology unit, comprising: a metrology sensor to measure avelocity of a gas flow; a processor to receive velocity data from themetrology sensor, to calculate a volume of the gas flow, and tocalculate totalized data of the volume having an accuracy that is withina threshold value; a memory device to store the totalized data; abattery to power the metrology sensor, the processor, and the memorydevice; and an interface configured to transmit the totalized data to anindex unit.
 9. The metrology unit as recited in claim 8, additionallycomprising: an enclosure of the metrology unit to enclose the metrologysensor, the processor, the memory device and the battery, wherein aninterior portion of the enclosure is configured to contain the gas flow.10. The metrology unit as recited in claim 8, additionally comprising: apower supply, within an enclosure of the metrology unit, configured toregulate power received from the battery.
 11. The metrology unit asrecited in claim 8, additionally comprising: an interface configured forwireless two-way communication with the index unit, wherein the wirelesstwo-way communication provides totalized data to the index unit.
 12. Themetrology unit as recited in claim 8, additionally comprising: acommunication device configured for inductive, optical or radiofrequency communication with the index unit.
 13. The metrology unit asrecited in claim 8, wherein metrology unit is configured for calculatingtotalized gas consumption data independent from actions of the indexunit.
 14. The metrology unit as recited in claim 8, wherein: themetrology sensor is configured to measure velocity of gas flow; and theprocessor calculates gas volume using data based on the gas flow withoutaction of the index unit.
 15. A method of measuring volume of a gasflow, comprising: directing the gas flow through an enclosure of ametrology unit, wherein a metrology sensor, a processor, a memory deviceand a battery are located in the enclosure; providing power to themetrology sensor, the processor, and the memory device from the battery;measuring a velocity of the gas flow, by operation of the metrologysensor; calculating a volume of the gas flow by operation of theprocessor, wherein the calculated volume of the gas flow comprisestotalized data that is accurate to within a threshold value; andtransmitting the totalized data to an index unit.
 16. The method ofclaim 15, additionally comprising: regulating power received from thebattery to control voltage at different current flows and battery chargelevels, wherein the regulating is performed within the enclosure of themetrology unit.
 17. The method as recited in claim 15, wherein thetransmitting comprises: communicating wirelessly with the index unit toprovide the totalized data to the index unit.
 18. The method as recitedin claim 15, wherein the transmitting comprises: transmitting thetotalized data to the index unit via at least one of inductive, opticalor radio frequency communication.
 19. The method as recited in claim 15,wherein the threshold value is selected to preclude need for gas volumecalculations by the index unit.
 20. The method as recited in claim 15,additionally comprising: operating a motor, powered by the battery, toshut off the gas flow, wherein the motor is located within the enclosureof the metrology unit.